The present invention relates to improvements in tooth treatment compositions. In particular, this invention relates to whitening compositions in a form that is capable of delivering fast whitening action.
The coronal portion of the tooth consists of enamel, dentin and the pulp. In the mouth of humans, the enamel is coated with an acquired pellicle. The tooth structures that are generally responsible for presenting a stained appearance are enamel, dentin, and the acquired pellicle. Tooth enamel is predominantly formed from inorganic material, mostly in the form of hydroxyapatite crystals, and further contains approximately 5% organic material primarily in the form of collagen. In contrast, dentin is composed of about 20% protein including collagen, the balance consisting of inorganic material, predominantly hydroxyapatite crystals, similar to that found in enamel. The acquired pellicle is a proteinaceous layer or matrix that forms continuously over the surface of the tooth. Although the acquired pellicle can be removed through intensive mechanical cleaning, it quickly regenerates soon thereafter.
Discoloration of teeth can result from intrinsic and/or extrinsic staining. Intrinsic staining occurs when staining compounds penetrate the enamel and even the dentin, or alternatively, such staining arises from sources within the tooth. Typically such staining can only be removed through chemical methods of tooth cleaning. Some dentifrices, like toothpastes, gels, and powders, contain active oxygen or hydrogen peroxide liberating bleaching agents including peroxides, percarbonates and perborates of the alkali and alkaline earth metals or complex compounds containing hydrogen peroxide.
Commonly used dental bleaching agent include hydrogen peroxide, carbamide peroxide (CO(NH2)2H2O2), or urea hydrogen peroxide, hydrogen peroxide carbamide, and perhydrol-urea. Carbamides and hydrogen peroxides are used in over-the-counter compositions as well as bleaching gels are dispensed by dentists and commonly dispensed ones include those containing hydrogen peroxide (available as “DayWhite” from Discus Dental, Inc.) and those containing a mixture of hydrogen peroxide and carbamide peroxide (available as “NiteWhite”, also from Discus Dental, Inc.).
Some prior art discloses the use of concentrated carboxypolymethylene compositions for producing a matrix material having a sufficiently high viscosity, low solubility in saliva, and is sufficiently tacky to retain and hold a dental tray positioned over the patient's teeth for a period greater than about 2 hours without any significant mechanical pressure from the dental tray so as to provide for the dental bleaching agent to be in contact with the tooth surfaces thereby providing bleaching of the tooth surfaces.
The amount of whitening obtained during tooth bleaching is dependent upon (1) the length of time each day the tray is worn; (2) the number of days the tray is worn; (3) the susceptibility of the teeth to the bleaching agent and (4) the concentration of active peroxides. For maximum whitening, an accelerated treatment time of approximately 18-20 hours per day is recommended.
The prolonged period needed for effective bleaching can be time consuming. Thus, any whitening system that can potentially reduce the time factor is desirable.